1. Field of the Invention
The present invention relates to a motor, particularly to a small motor having a distinctive connection structure between a core and a terminal block.
2. Description of Related Art
Recently, a small stepping motor for driving a head of an FD, a CD, or a DVD have been in use. Among the stepping motors for such purposes, motors each having a diameter of at most 12 mm with double-layered coils are widely available. In Japanese Unexamined Patent Publication No. 2003-88062, the applicant of the present invention previously proposed a motor, which is based on a stepping motor of this type. This motor includes a rotor that has a rotation shaft and magnets fixed to the rotation shaft, a stator that has paired inner cores and outer cores also serving as a case, and a resin coil bobbin that is molded integrally with the paired inner cores so as to allow coils to be wound therearound.
The paired inner cores each include a disk part and pole teeth that axially extend from an inner circumferential edge of the disk part. Two cores configuring the paired inner cores are wrapped with a resin such that the disk parts face back to back, and the coil bobbin is formed to have coil winding parts axially on respective sides, thereby obtaining an insert molded component. Terminal pins to be connected with the coils are supported by a terminal block that is molded simultaneously with the coil bobbin.
FIG. 7A is a perspective view showing an outer appearance of the insert molded component, and FIG. 7B is a view showing a structure of a portion where the terminal block is connected. Terminal pins 32′ to be connected with coils 12a and 12b are supported by a terminal block 30′ that which is continuously provided to a tip end of an extending part 38′ extending outward from a portion corresponding to disk parts of a coil bobbin 22′. The extending part 38′ surrounds with a resin “J” a terminal block holding part 16′ that extends from disk parts 14′ of paired inner cores 11′. The terminal block holding part 16′ has a straight terminal block facing end 17′ to face the terminal block 30′.
It is desired to further the reduction in size of the small motors. Reduction in size of the terminal block and the periphery thereof inevitably results in reduction of a space “S” between base ends of the terminal pins 32′ and the terminal block holding part 16′ of the paired inner cores 11′, as well as reduction in width, namely thickness, of the resin “J” that wraps the terminal block holding part 16′. However, as the width of the resin “J” is reduced to cause reduction in thickness thereof, the strength to support the terminal block 30′ with respect to the paired inner cores 11′ is reduced, such that the terminal block is more easily damaged.